1. Field of the Invention
The invention relates to a cooling apparatus, and more particularly to a cooling apparatus that cools a charger for charging a storage battery using a vapor compression refrigeration cycle.
2. Description of Related Art
In recent years, hybrid vehicles (HVs), fuel cell vehicles, electric automobiles, and so on which travel using driving force from a motor have come to attention as a countermeasure to environmental problems. In this type of vehicle, electric devices such as the motor, a generator, an inverter, a converter, and a battery generate heat during power transfer. It is therefore necessary to cool these electric devices. Hence, techniques in which a heat generating body is cooled using a vapor compression refrigeration cycle employed as a vehicle air-conditioning apparatus have been proposed.
For example, Japanese Patent Application Publication No. 2005-90862 (JP 2005-90862 A) discloses a cooling system in which heat generating body cooling means for cooling a heat generating body is provided in a bypass passage that bypasses a pressure reducer, an evaporator, and a compressor of an air-conditioning refrigeration cycle.
Incidentally, when a heating operation is performed using a vapor compression refrigeration cycle, a heat exchange capacity deteriorates due to frost formation on an external heat exchanger. In response to this problem, Japanese Patent Application Publication No. 6-24235 (JP 6-24235 A) proposes a technique for preventing frost formation on an external heat exchanger by combining air-conditioning using a heat storage system with air-conditioning using a vapor compression refrigeration cycle such that during a heating operation, warm air generated by an external heat exchanger is supplied to an external heat exchanger of the vapor compression refrigeration cycle.
Meanwhile, various techniques for cooling a charger installed in a vehicle have been proposed in the related art. For example, Japanese Patent Application Publication No. 2010-81704 (JP 2010-81704 A) discloses a technique in which a circulation passage is formed to connect a charger to a radiator and circulate cooling water therebetween, heat is discharged effectively from the cooling water flowing through the radiator by driving a cooling fan to transmit air to the radiator, the cooling water heat-discharged by the radiator is caused to flow to the charger by driving a pump, and heat exchange is performed between the charger and the cooling water such that the charger is cooled.
Japanese Patent Application Publication No. 4-275492 (JP 4-275492 A) discloses a cooling apparatus in which a charger that charges a battery by rectifying power from a power supply is provided in an electric automobile, a pipe forming a coolant circulation path is laid so as to pass through the charger, and the coolant is circulated through the coolant circulation path using a coolant pump.
Japanese Patent Application Publication No. 2009-143509 (JP 2009-143509 A) discloses a technique in which a battery that generates heat during charging is disposed such that heat exchange occurs between the battery and cooling air, whereby an amount of heat generated during charging is radiated to the cooling air so as to cool the battery. JP 2009-143509 A also discloses a technique in which warm air warmed by waste heat from the battery passes through a heat exchanger provided in a heat pump for use during an evaporation process such that an amount of heat included in the warm air is recovered as a heat source for the evaporation process of a heat cycle.
When an air-conditioning apparatus employing a vapor compression refrigeration cycle is used during cold weather or in a cold location, a problem occurs in that frost forms on the external heat exchanger during the heating operation. When frost forms on the external heat exchanger, heat exchange between a refrigerant and atmospheric air is impaired, and therefore a defrosting operation is performed by forcibly implementing a cooling operation in order to remove the frost. During the defrosting operation, a compressor must be activated even though the heating operation is not required, and therefore a power consumption of the compressor increases. JP 6-24235 A discloses a technique for avoiding the defrosting operation by preventing frost from forming on the external heat exchanger, but in this case, a system is required to supply warm air to the external heat exchanger, and therefore an apparatus configuration becomes complicated and an increase in power consumption occurs due to the need to operate the pump.